This invention relates to a video switcher system with modular architecture.
FIG. 1 illustrates a conventional video mixing system, or switcher, in simplified block form. The FIG. 1 switcher comprises a source selector 2 which receives multiple video input signals, e.g. from external video signal sources, and provides selected ones of these input signals to mix/effects amplifiers (M/Es) 4. Each M/E receives at least two video input signals and combines them under control of signals provided by an operator interface 6 to provide on output video signal. The output signal provided by any of the M/Es 4 can be re-entered into another M/E through re-entry terminals 8 of the source selector 2. The output signal of the FIG. 1 switcher is taken from a reduced function program/preset M/E 10.
Conventional switchers are fixed in their architecture at the time of manufacture, and accordingly the number of source selector inputs, the number of M/Es and the type and capabilities of each M/E cannot be changed. Therefore, in order to upgrade the switcher capability of a television studio, it has previously been necessary to replace the entire swticher. A user with limited resources might not be able to afford to replace his switcher. A user with greater resources will generally buy a switcher whose capabilities are limited only by the maximum anticipated requirements over the lifetime of the studio in which it is installed, and therefore the switcher will be under utilized much of the time. Since the functional components of one switcher cannot be shared with another switcher, a production facility with two or more studios may find itself handling simultaneously one production that is too large for its largest switcher and another production that under utilizes the smallest available switcher.